Identity theft and black market sales of counterfeit goods are significant problems faced with increasing regularity in today's world. Each year many millions of dollars are lost through the fraudulent use of non-authentic documents and branded goods. The increasing sophistication of optical scanners, copy machines and other devices used for replicating items and identification labels continues to enhance the counterfeiter's ability to produce fraudulent documents and other imitations which are of sufficient quality to often go undetected.
One method of providing increased security involves applying to the article some form of indicia, typically a text string or other image, that has been encoded so that the image cannot be viewed by the unassisted eye. The encoded image can be viewed only through the use of a decoding device that “re-assembles” the image as it appeared prior to being encoded.
High resolution scanning devices create a possibility that even these images may be subject to reproduction. Replication devices, such as optical scanners for example, generally operate by detecting reflection of light cast onto an item by the scanner. Areas of the item that have large amounts of pigment will absorb more light than areas that have little or no pigment. The scanner may measure the amount or intensity of the reflected light that is recorded as computer data by the scanner. This data is then used by the scanner to generate a replica of the scanned item, usually as either a printed copy or a digital image. This replica may be of sufficient quality that the encoded printed indicia may also be replicated. In such a case, using the decoder to view the replicated article may not reveal its counterfeit nature.